Korean stocks started 1.66 percent lower Friday after a 10 percent gain the previous session as a prolonged Iran crisis rekindled oil supply woes. The benchmark Korea Composite Stock Price Index (KOSPI) opened at 5,491.02, down 92.88 points from the previous session. The index has suffered an extreme rout this week in the wake of the Middle East conflict, tumbling 7.24 percent and 12.06 percent on Tuesday and Wednesday, respectively, before soaring 9.63 percent Thursday.